Equis ISSN 2398-2977

Skin: staphylococcal folliculitis

Synonym(s): Acen, heat rash, saddle scab, summer rash, summer scab, sweating eczema, saddle boils, grease heel, scratches, tail rot

Contributor(s): Timothy Nuttall

Introduction

  • Inflammation of the hair follicle caused by Staphylococcal bacteria.
  • Cause:Staphylococcus aureus  Staphylococcus aureus    Staphylococcus spp  ,S. intermedius,S. hyicus.
  • Signs: papules, pustules, crusts, scales, nodules and annular areas of alopecia over the saddle and tack areas.
  • Diagnosis: history, examination, cytology, bacterial culture, histopathology.
  • Treatment: topical antibacterial agents, systemic antibiotics.
  • Prognosis: good.

Pathogenesis

Etiology

  • Staphylococcus aureus  Staphylococcus aureus  is the most common, followed byS. intermedius, and rarelyS. hyicus.

Predisposing factors

General
  • Hot and humid environment.
  • Frequent riding/heavy work load.
  • High insect/tick population.
  • Poorly groomed horses.

Pathophysiology

  • Bacterial infection of the hair follicle secondary to cutaneous trauma.
  • Advanced lesions may   →   rupture of the hair follicle (furunculosis) with corresponding dermal inflammation.
  • Damage to skin, eg insect bite, trauma   →    staphylococcal bacteria invades and infects the hair follicle    →   small papule forms and overlying hairs may become erect    →   a pustule may arise from the papule, rupture and form a crust or    →   papule enlarges and may develop a central ulcer with purulent discharge    →   hair follicle may eventually rupture resulting in free hair shafts in the dermis (furunculosis) and an inflammatory foreign body reaction.

Epidemiology

  • Can be spread via fomites, eg shared tack.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Pilsworth R C & Knottenbelt D C (2007) Bacterial folliculitis. Equine Vet Educ 19 (6), 324-325 VetMedResource.
  • Fadok V A (1995) An overview of equine dermatoses characterized by scaling and crusting. Vet Clin North Am Equine Pract Derm 11 (1), 43-51 PubMed.

Other sources of information

  • Smith B P (1996) Large Animal Internal Medicine. Mosby, USA.
  • Scott D W (1988) Large Animal Dermatology. W B Saunders, USA.


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